Deprecations and removals in Chrome 66

ImageCapture.setOptions() removed

Current thinking on setting device options is to use the
constrainable pattern
. Consequently this property was removed from the
ImageCapture specification
. Since this method appears to have little to no use on production websites, it
is being removed. A replacement method is not available at this time.

Service worker: disallow CORS responses for same-origin requests

Previous versions of the service worker specification allowed a service worker
to return a CORS response to a same-origin request. The thinking was that the
service worker could read from a CORS response to create a completely synthetic
response. In spite of this, the original request URL was maintained in the
response. So outerResponse.url exactly equaled url and innerResponse.url
exactly equaled crossOriginURL.

A recent change to the Fetch specification
requires that Response.url be exposed if it is present. A consequence of this
is scenarios in which self.location.href returns a different origin than
self.origin. To avoid this, service workers are no longer allowed to return
CORS responses for same origin requests.

WebAudio: dezippering removed

Web audio originally shipped with dezippering support. When an AudioParam value
was set directly with the value setter, the value was not updated immediately.
Instead, an exponential smoother was applied with a time constant of about 10 ms
so that the change was done smoothly, limiting glitches. It was never specified
which parameters had smoothing and what the time constant was. It wasn’t even
obvious if the actual time constant was the appropriate value.

After much discussion
, the working group removed dezippering from the spec. Now, the value is changed
immediately when set. In place of dezippering, it is recommended that developers
use the existing AudioParam.setTargetAtTime() method to do the dezippering,
giving you full control on when to apply it, how fast to change, and on which
parameters should be smoothed.

Removing this reduces developer confusion which audio parameters support dezippering.

CSS position values with three parts deprecated

Recently specifications have required that new properties accepting position
values not support values with three parts. It's believed this approach makes
processing shorthand syntax easier. The current version of the
CSS Values and Units Module applies
this requirement to all CSS position values. As of Chrome 66, three-part
position values are deprecated. Removal is expected in Chrome 68, around July 2018.

Deprecation policy

To keep the platform healthy, we sometimes remove APIs from the Web Platform
which have run their course. There can be many reasons why we would remove an
API, such as:

They are superseded by newer APIs.

They are updated to reflect changes to specifications to bring alignment
and consistency with other browsers.

They are early experiments that never came to fruition in other browsers
and thus can increase the burden of support for web developers.

Some of these changes will have an effect on a very small number of sites. To
mitigate issues ahead of time, we try to give developers advanced notice so
they can make the required changes to keep their sites running.

Set warnings and give time scales in the Chrome DevTools Console when usage
is detected on the page.

Wait, monitor, and then remove the feature as usage drops.

You can find a list of all deprecated features on chromestatus.com using the
deprecated filter and removed features by applying the
removed filter.
We will also try to summarize some of the changes, reasoning, and migration
paths in these posts.

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